Core C. O'Flynn
Internet-Draft Atmel Corporation
Intended status: Informational B. Sarikaya
Expires: January 13, 2011 Huawei USA
R. Cragie
Pacific Gas and Electric
July 12, 2010
Initial Configuration of Resource-Constrained Devices
draft-oflynn-core-bootstrapping-01
Abstract
The Internet of Things is marching its way towards completion. Nodes
can use standards from the 6LoWPAN and ROLL WG to achieve IP
connectivity. IEEE Standards ensure connectivity at lower layers for
resource-constrained devices. Yet a central problem remains at a
more basic layer without a suitable answer: how to initially
configure the network. Without configuration the network never
advances beyond a large box of nodes. Current solutions tend to be
specific to a certain vendor, node type, or application.
This document outlines exactly what problems are faced in solving
this problem. General problems faced in any low-power wireless
network are outlined first; followed by how these apply to
bootstrapping. A selection of currently proposed techniques is
presented. From these a more generic approach is presented, which
can solve the problem for a wide range of situations.
An emphasis is on performing this bootstrapping in a secure manner.
This document does not cover operation of the network securely. This
document does provide the basis for allowing the network to operate
securely however, by providing standard methods for key exchanges and
authentication.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 13, 2011.
Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. What is Bootstrapping? . . . . . . . . . . . . . . . . . . 4
1.2. Why IETF? . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3. Why a New Standard? . . . . . . . . . . . . . . . . . . . 5
2. Bootstrapping Architecture . . . . . . . . . . . . . . . . . . 5
3. Communications Channel . . . . . . . . . . . . . . . . . . . . 6
3.1. Supported Communication Channels . . . . . . . . . . . . . 7
4. Bootstrap Security Method . . . . . . . . . . . . . . . . . . 7
4.1. None . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.2. EAP Methods . . . . . . . . . . . . . . . . . . . . . . . 8
4.3. Asymmetric with User Authentication, Followed by
Symmetric . . . . . . . . . . . . . . . . . . . . . . . . 8
4.4. Asymmetric with Certificate Authority, Followed by
Symmetric . . . . . . . . . . . . . . . . . . . . . . . . 8
4.5. Cryptographically Generated Address Based Address
Ownership Verification . . . . . . . . . . . . . . . . . . 8
5. Bootstrap Protocol . . . . . . . . . . . . . . . . . . . . . . 8
6. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 9
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
11.1. Normative References . . . . . . . . . . . . . . . . . . . 10
11.2. Informative References . . . . . . . . . . . . . . . . . . 10
Appendix A. Examples of Node Configuration . . . . . . . . . . . 11
A.1. Smart Energy . . . . . . . . . . . . . . . . . . . . . . . 11
A.1.1. Initial Meter Installation . . . . . . . . . . . . . . 11
A.1.2. Home Expansions . . . . . . . . . . . . . . . . . . . 11
A.2. Consumer Products . . . . . . . . . . . . . . . . . . . . 11
A.2.1. Connecting DVD Remote to DVD Player . . . . . . . . . 11
A.2.2. Adding a TV to a network with a DVD player and
remote . . . . . . . . . . . . . . . . . . . . . . . . 12
A.2.3. Providing GPS Location Data . . . . . . . . . . . . . 12
A.3. Commercial Building Automation . . . . . . . . . . . . . . 12
A.3.1. Light Installation . . . . . . . . . . . . . . . . . . 12
Appendix B. Example Exchanges . . . . . . . . . . . . . . . . . . 12
B.1. Smart Energy: Meter Manufacture . . . . . . . . . . . . . 12
B.2. Smart Energy: Meter Installation . . . . . . . . . . . . . 12
B.3. Smart Energy: Home Expansion . . . . . . . . . . . . . . . 12
B.4. Consumer: Connecting DVD Remote to DVD Player . . . . . . 13
B.5. Consumer: Adding a TV to a network with a DVD player
and remote . . . . . . . . . . . . . . . . . . . . . . . . 14
B.6. Consumer: Providing GPS Location Data . . . . . . . . . . 16
B.7. Commercial: Building Automation . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16
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1. Introduction
Familiarity with constrained network types is assumed here.
Documents produced in the 6LoWPAN, ROLL, and CoRE Working Groups
(WGs) would be a useful reference for the reader. In particular RFC
4919 [RFC4919] from 6LoWPAN, RFC 5548 [RFC5548] and RFC 5673
[RFC5673] from ROLL, and a paper by Romer and Mattern [ROMER04].
Familiarity with application specific examples is also useful, such
as Zigbee or Smart Energy groups.
A summary of those will be presented, as far as network requirements
are concerned. The general network requirements will be further
concentrated into requirements surrounding only the bootstrapping
issues.
A number of solutions which are currently in use will be presented
and compared to the requirements. From these the requirements of the
final solution is identifiable, and a proposal is made on this.
Note this document has considerable extra information that is not
designed to be worked into the final I-D. It also has some example
specifications of particular applications that would not be present
in the final version as they are out of scope of the proposed working
group. As a general guide they are very useful, but realistically
will be split off to either another I-D or some other location.
1.1. What is Bootstrapping?
Node configuration is known as bootstrapping in this document.
Bootstrapping is any processing required before the network can
operate. Typically this will require a number of settings to be
transferred between nodes at all layers. This could include anything
from link-layer information (i.e., wireless channels, link-layer
encryption keys) to application-layer information (i.e., network
names, application encryption keys).
Bootstrapping is complete when settings have been securely
transferred prior to normal operation in the network.
1.2. Why IETF?
The bootstrapping problem is not specific to any MAC or PHY. This
problem exists across any two nodes which have no previous knowledge
of each other. In particular, this problem is complicated when the
nodes are resource-constrained and may not have an advanced user
interface. The IETF is instrumental in defining standards which will
be used by The Internet of Things. Ensuring these standards can be
used across nodes and networks requires some form of bootstrapping
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which any node can use.
Existing standards will be used as much as possible in this document.
The method proposed here should work across many different underlying
layers. It could be used to allow two nodes on the same physical
network to join at the physical layer, or allow two nodes on an
incompatible physical network to join at the IPv6 layer.
1.3. Why a New Standard?
Simply put, no existing standard brings together all the required
aspects. At lower layers, standards exist to solve the problem in
special cases. Examples are Wi-Fi Protected Setup, Bluetooth
Pairing, or ZigBee solutions such as Zigbee RF4CE [RF4CE]. As will
be discussed later, these are not flexible enough to run on the wide
variety of nodes which a smart network will use.
At higher layers, standards exist to perform a secure authentication
or service discovery. However these standards almost always assume
the two nodes have some existing way of communicating, such as being
plugged into the same network. This will often not be the case.
Thus this document is aimed to bridge this gap. Many existing
standards can be applied to solve the problem (e.g. EAP), but some
guidance on their use is required to ensure all implementations
interoperate.
2. Bootstrapping Architecture
In order to provide a flexible architecture, the bootstrapping method
is split into five distinct areas. The five areas are a 'user
interface', 'bootstrap profile', 'security method', 'bootstrap
protocol', and the 'communications channel'.
The user interface provides both user input and user output. Simple
nodes may only have a push-button and LED, more complex nodes may
have a graphical display and keyboard. The user interface provides
interaction between the user and bootstrapping methods. The user
interface would be used during bootstrapping as an OOB channel. It
may also be used to specify bootstrapping policies.
The user interface provides the interaction between the user and the
bootstrap protocol. The user interface will vary depending on the
capabilities of the node. Examples might include a push-button and
LED on simple nodes, to full-blown graphical user interfaces. Note
that a 'bootstrapping tool' used to initially deploy a network is
just a special user interface. This allows a very uniform protocol
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in deployment and use of networks.
User interface is out-of-scope and will not be further discussed.
Two nodes communicate through some channel. For our purposes this is
split into the 'control channel' and 'data channel'. The control
channel is used for the bootstrap protocol, and the data channel is
used during normal network operation. A node may support multiple
control or data channels. When the control and data channels are the
same, the bootstrapping is done In Band (IB). When the control and
data channels are different, the bootstrapping is performed Out Of
Band (OOB). An 802.15.4 network for instance would use an 802.15.4
control channel for IB bootstrapping, but a control channel of
perhaps IrDA or USB for OOB bootstrapping.
The 'bootstrap profile' defines what information should be exchanged
during the process. A single node may run the protocol multiple
times with different profiles. If the user wishes to associate a new
lightswitch, the protocol is first run with the '802.15.4 Wireless
Profile', through which it learns the channel and PAN-ID. The node
then runs a 'Security Exchange Profile' to learn the needed
encryption keys. Finally it runs a 'Lightswitch Association Profile'
through which it learns which light to associate with.
The 'security method' defines supported security methods for
bootstrapping. The supported security methods will depend on the
control channel and bootstrap profile. In one node if the control
channel is secure, then a simple clear-text security method is
supported. For example when a physical connection between two nodes
is used, the control channel is considered secure. However when the
BTL is not secure, this clear-text security method is not supported.
The 'bootstrap profile' additionally defines allowed security
methods. Higher security nodes may outlaw ever performing a clear-
text exchange, even if the control channel is deemed secure.
The 'bootstrap protocol' defines the actual messages exchanged during
bootstrapping. The messages are used to transfer between nodes data,
node information, and network state. The selected security method
runs on top of the control channel, such as EAP-GPSK etc.
3. Communications Channel
The communications channel is the method used between two nodes to
communicate. There are two main communication channels: the
'control' and 'data' channels. The control channel is used during
bootstrapping, and the data channel is used during network operation.
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3.1. Supported Communication Channels
There is no limit on what communications channels are supported. The
following gives an example of several supported channels:
o IEEE 802.15.4
o Power-Line Communications
o IrDA
o RFID
o Some simple physical link
o Cellular
o Ethernet
o IPv6
o Wi-Fi
Depending on the node's function, it may use different channels as
the data or control channel. Nodes may have multiple data and/or
control channels as wel.
4. Bootstrap Security Method
The bootstrap security method defines allowable security methods. A
node may choose to support or use a subset of these methods. This is
NOT the security architecture used for the application, but only the
security used during bootstrapping. Typically some high-security
method is used to generate a shared secret, which then switches to
simplier symmetric encryption to secure the actual bootstrapping
channel. The techniques negotiated should take advantage of hardware
resources available, such as hardware encryption accelerators on an
end node.
4.1. None
This is the simplist security method. No encryption or
authentication is provided, messages are exchanged completely in
clear-text. It is assumed some other layer provides security, such
as a physical connection between devices.
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4.2. EAP Methods
EAP-TLSv1.2 can be used as the authentication method [RFC5246].
EAP-GPSK can be used as the authentication method [RFC5433]. Keys
must be pre-shared through some other method.
4.3. Asymmetric with User Authentication, Followed by Symmetric
A Diffie-Hellman style key exchange is used to generate a shared
secret. The authentication will be provided by the user, by
confirming cryptographic signatures between two devices. With the
shared secret generated through the DH, some symmetric encryption is
used to secure the actual bootstrapping channel.
4.4. Asymmetric with Certificate Authority, Followed by Symmetric
Public key exchanges are used (aka: DH again), but with a Certificate
Authority. Once a shared secret exists, symmetric encryption is used
to secure the actual bootstrapping channel.
4.5. Cryptographically Generated Address Based Address Ownership
Verification
A node may generate the global unique address using different
techniques other than the stateless address autoconfiguration. For
example, Cryptographically Generated Addresses (CGA) [RFC3972] is a
type of global unique address that can be used to verify the address
ownership. When the node uses CGA, it MUST execute SeND protocol
[RFC3971]. In a 6LOWPAN network, a modified 6LOWPAN ND Protocol
[I-D.ietf-6lowpan-nd] must be executed between the node and the edge
router.
5. Bootstrap Protocol
The bootstrap protocol defines several messages which can be sent
over the BTL. The bootstrap protocol is a small wrapper around the
standard authentication functions used, such as EAP etc. The
bootstrap protocol will negotiate allowable standards between nodes.
When a TV is joining a remote control for example, the bootstrap
protocol must understand that the remote control has very limited
feedback to the user. Hence the method selected must not rely on a
complex user interface on the remote, even though the TV has a
complex interface available.
Specifics TBD.
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6. Conclusion
Initial configuration of a network is essential to interoperability.
This process is known as bootstrapping, and a variety of solutions
have been proposed previously. An analysis of the requirements shows
that no single solution is likely to meet all the requirements,
instead multiple solutions will be picked. At least one of these
must remain capable of running on the most resource constrained
nodes, ensuring that all nodes are capable of at least a single
common communication channel.
This document helps to focus on a method of solving this problem in a
flexible and extensible way. It is very much a work in progress, and
is expected to undergo radical changes before it becomes complete.
Please comment on the mailing list or add missing sections as you see
fit.
7. Security Considerations
TBD.
8. IANA Considerations
None.
9. Acknowledgements
Thanks to Zach Shelby for editing, comments, and overall assistance.
10. IANA Considerations
This memo includes no request to IANA.
All drafts are required to have an IANA considerations section (see
the update of RFC 2434 [I-D.narten-iana-considerations-rfc2434bis]
for a guide). If the draft does not require IANA to do anything, the
section contains an explicit statement that this is the case (as
above). If there are no requirements for IANA, the section will be
removed during conversion into an RFC by the RFC Editor.
11. References
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11.1. Normative References
[RF4CE] ZigBee Alliance, "Zigbee RF4CE Specification Version
1.00", March 2009.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
Levkowetz, "Extensible Authentication Protocol (EAP)",
RFC 3748, June 2004.
[RFC4919] Kushalnagar, N., Montenegro, G., and C. Schumacher, "IPv6
over Low-Power Wireless Personal Area Networks (6LoWPANs):
Overview, Assumptions, Problem Statement, and Goals",
RFC 4919, August 2007.
[RFC5548] Dohler, M., Watteyne, T., Winter, T., and D. Barthel,
"Routing Requirements for Urban Low-Power and Lossy
Networks", RFC 5548, May 2009.
[RFC5673] Pister, K., Thubert, P., Dwars, S., and T. Phinney,
"Industrial Routing Requirements in Low-Power and Lossy
Networks", RFC 5673, October 2009.
[ROMER04] Romer, K. and F. Mattern, "The design space of wireless
sensor networks", IEEE Wireless Communications, vol. 11,
no. 6, pp. 54-61, December 2004.
11.2. Informative References
[I-D.ietf-6lowpan-nd]
Shelby, Z., Chakrabarti, S., and E. Nordmark, "Neighbor
Discovery Optimization for Low-power and Lossy Networks",
draft-ietf-6lowpan-nd-10 (work in progress), June 2010.
[I-D.narten-iana-considerations-rfc2434bis]
Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs",
draft-narten-iana-considerations-rfc2434bis-09 (work in
progress), March 2008.
[RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
June 1999.
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552,
July 2003.
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[RFC3971] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure
Neighbor Discovery (SEND)", RFC 3971, March 2005.
[RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)",
RFC 3972, March 2005.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC5433] Clancy, T. and H. Tschofenig, "Extensible Authentication
Protocol - Generalized Pre-Shared Key (EAP-GPSK) Method",
RFC 5433, February 2009.
Appendix A. Examples of Node Configuration
Before any detail on methods is explored, the following section will
provide various examples this document could cover. Exact
requirements will be brought forward in subsequent sections. For the
reader's general understanding this section is placed to give an idea
of an acceptable usage scenario.
A.1. Smart Energy
A.1.1. Initial Meter Installation
The meter is initially loaded with code and network keys through a
physical interface at the factory. The meter is installed at a
customers home, and configured by the installer through the backbone
link (via GSM modem, etc). Both operations can be performed through
methods defined herein.
A.1.2. Home Expansions
The user wishes to join a thermostat onto the network. They press a
button on the thermostat, which enters join mode. They press a
button on the smart meter, which allows nodes to join the network.
The devices both have displays, so they display a certain number
which the user verifies match on both devices. The thermostat has
now securely joined the network.
A.2. Consumer Products
A.2.1. Connecting DVD Remote to DVD Player
The user pushes a join button on the DVD remote and DVD player. The
devices find each other, and blink in unison to indicate to the user
which two devices will join. The user presses the button to confirm
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this, and the two devices are now joined together.
A.2.2. Adding a TV to a network with a DVD player and remote
The user then presses the join button on the DVD player and TV. The
devices again find each other and blink in unison, with the addition
that the remote control also blinks to indicate it is present in the
network.
A.2.3. Providing GPS Location Data
A user has a simple GPS receiver (that has no user interface) they
wish to broadcast location data with. The user switches on their
camera, and enters a PIN from the base of the GPS. The user can now
view GPS information such as satellite health from their camera. In
addition photos are automatically tagged with location information.
A.3. Commercial Building Automation
A.3.1. Light Installation
The electrician installs the light fixture. Each light has a barcode
printed on it. They use a handheld barcode scanner tool, which acts
as the commissioning tool. When they scan a barcode with the tool,
the tool asks the electrician to enter some additional information
such as light fixture location. The tool securely registers the
light fixture on the network, along with setting parameters inside
the light fixture.
Appendix B. Example Exchanges
The following details how the protocol handles certain conditions and
situations through examples. Note that each example is a more
detailed description of the examples in Appendix A.
B.1. Smart Energy: Meter Manufacture
B.2. Smart Energy: Meter Installation
B.3. Smart Energy: Home Expansion
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B.4. Consumer: Connecting DVD Remote to DVD Player
Supported User Interface Profiles
+----------------+------------+----------------+
| Profile | DVD Player | Remote Control |
+----------------+------------+----------------+
| none | Y | Y |
| simple | Y | Y |
| numerical | Y | N |
| alphanumerical | Y | N |
| Graphical | Y | N |
+----------------+------------+----------------+
Supported Bootstrap Transport Layers
+----------+------------+----------------+
| Layer | DVD Player | Remote Control |
+----------+------------+----------------+
| Physical | Y | Y |
| 802.15.4 | Y | Y |
| IrDA | Y | N |
+----------+------------+----------------+
Supported Security Methods
+------------------+------------+----------------+
| Method | DVD Player | Remote Control |
+------------------+------------+----------------+
| None | Y | Y |
| EAP | Y | N |
| Asymmetric, User | Y | Y |
| Asymmetric, CA | Y | N |
+------------------+------------+----------------+
The DVD player and remote control have a number of ways in which they
could be joined together. The remote control does not have any
unique identifier printed on it, thus no pre-shared key can be
identified. This leaves either an unsecure joining method, or some
asymmetric security method.
The remote control has a button on it for 'join', as does the DVD
player. The user pushes the button on the DVD player, and then
pushes the button on the remote control. Based on the UI profile,
this causes the following to occur:
o DVD Player scans for existing network in advertise mode. Finding
none, it starts a new network and that network enters advertise
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mode.
o The DVD remote scans for a network, and then finds the DVD
player's network.
o The devices generate a shared secret (ie: Diffie-Hellman), and
both blink their LED in a unique pattern based on this shared
secret.
o The user user confirms both devices are blinking the same pattern,
as both LEDs are blinking in unison.
o The DVD player displays 'JOIN OK' on it's LCD panel.
B.5. Consumer: Adding a TV to a network with a DVD player and remote
This network will have three devices: a TV, a DVD Player, and a
Remote Control. The user will run the bootstrap protocol between the
TV and Remote Control in this example, although it could also be run
between the TV and DVD player.
Supported User Interface Profiles
+----------------+----+----------------+
| Profile | TV | Remote Control |
+----------------+----+----------------+
| none | Y | Y |
| simple | Y | Y |
| numerical | Y | N |
| alphanumerical | Y | N |
| Graphical | Y | N |
+----------------+----+----------------+
Supported Bootstrap Transport Layers
+----------+----+----------------+
| Layer | TV | Remote Control |
+----------+----+----------------+
| Physical | Y | Y |
| 802.15.4 | Y | Y |
| IrDA | Y | N |
+----------+----+----------------+
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Supported Security Methods
+------------------+----+----------------+
| Method | TV | Remote Control |
+------------------+----+----------------+
| None | Y | Y |
| EAP-GPSK | Y | N |
| Asymmetric, User | Y | Y |
| Asymmetric, CA | Y | N |
+------------------+----+----------------+
The TV and remote control have a number of ways in which they could
be joined together. The remote control does not have any unique
identifier printed on it, thus no pre-shared key can be identified.
This leaves either an unsecure joining method, or some asymmetric
security method.
The remote control has a button on it for 'join', as does the TV. In
this example two sequence will be considered: where the TV button is
pressed first, and where the remote control button is pressed first.
If the TV join button is pressed first:
o TV scans for existing networks in advertise mode. Finding none,
it starts a new network and that network enters advertise mode.
o The remote scans for a network, and then finds the TV's network.
o The remote informs the TV it is on an existing network, and thus
will require the TV to join this network.
o The devices generate a shared secret, and both blink their LED in
a unique pattern.
o The DVD player in addition blinks, so the user is informed that if
they confirm the join action the resulting network will have all
three devices in it.
o The user confirms both devices are blinking the same pattern, as
both LEDs are blinking in unison.
o The TV displays 'JOIN OK' onscreen, along with any information
about the network it just joined.
If the remote control join button is pressed first:
o Remote control scans for existing networks in advertise mode.
Finding none, it advertises it's network.
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o The TV scans for a network, and then finds the remote control's
network.
o The devices generate a shared secret, and both blink their LED in
a unique pattern.
o The DVD player in addition blinks, so the user is informed that if
they confirm the join action the resulting network will have all
three devices in it.
o The user confirms both devices are blinking the same pattern, as
both LEDs are blinking in unison.
o The TV displays 'JOIN OK' onscreen, along with any information
about the network it just joined.
B.6. Consumer: Providing GPS Location Data
B.7. Commercial: Building Automation
Authors' Addresses
Colin Patrick O'Flynn
Atmel Corporation
Colorado Springs, Colorado
USA
Phone:
Email: colin.oflynn@atmel.com
Behcet Sarikaya
Huawei USA
1700 Alma Dr. Suite 500
Plano, TX 75075
Email: sarikaya@ieee.org
Robert Cragie
Pacific Gas and Electric
89 Greenfield Crescent
Wakefield, UK WF4 4WA
Email: robert.cragie@gridmerge.com
O'Flynn, et al. Expires January 13, 2011 [Page 16]